由于缺乏材料dispatch_set_target_queue
,我来这里寻求帮助,所以谢谢!
这是我的测试代码:
dispatch_queue_t mySerialDispatchQueue1 = dispatch_queue_create("come.itenyh", NULL);
dispatch_queue_t mySerialDispatchQueue2 = dispatch_queue_create("come.itenyh1", NULL);
dispatch_set_target_queue(mySerialDispatchQueue1, mySerialDispatchQueue2);
dispatch_async(mySerialDispatchQueue1, ^{[self task:@"s1"];});
dispatch_async(mySerialDispatchQueue2, ^{[self task:@"p1"];});
dispatch_async(mySerialDispatchQueue1, ^{[self task:@"s2"];});
- (void)task:(NSString *)taskid
{
NSLog(@"Now executing taskid:%@", taskid);
[NSThread sleepForTimeInterval:5];
}
现在如果我设置
dispatch_set_target_queue(mySerialDispatchQueue2, mySerialDispatchQueue1);
那么结果是:
2014-04-16 22:23:49.581 ITGCDLearning[66758:1303] Now executing taskid:s1
2014-04-16 22:23:54.585 ITGCDLearning[66758:1303] Now executing taskid:s2
2014-04-16 22:23:59.586 ITGCDLearning[66758:1303] Now executing taskid:p1
相反,如果我设置
dispatch_set_target_queue(mySerialDispatchQueue1, mySerialDispatchQueue2);
那么结果是:
2014-04-16 22:28:37.910 ITGCDLearning[66795:1303] Now executing taskid:s1
2014-04-16 22:28:42.913 ITGCDLearning[66795:1303] Now executing taskid:p1
2014-04-16 22:28:47.915 ITGCDLearning[66795:1303] Now executing taskid:s2
我知道dispatch_set_target_queue
功能可以
我认为是第二点导致了我的代码中的结果,但并不真正知道具体细节。有人可以向我解释一下吗?